The present disclosure relates to systems and methods for medical imaging. More particularly, the present disclosure relates to systems and method for electron paramagnetic resonance imaging (EPRI) using a traveling wave regime to generate electromagnetic fields.
Electron paramagnetic resonance imaging (EPRI) is a low-cost and highly-specific molecular imaging modality. Molecular imaging describes biomedical imaging techniques that derive specific contrast based on the molecular biology of the associated tissue being assessed, and is most often associated with positron emission tomography (PET). EPRI can also be used to non-invasively measure tissue properties such as oxygenation, pH, and redox status and has additional demonstrated applications in cell tracking, radiation dosimetry, and non-biological applications in materials science. Compared to other imaging modalities that utilize response to magnetic fields as a mechanism to elicit contrast, such as magnetic resonance imaging (MRI), EPRI requires substantially lower magnetic fields, allowing the use of non-superconducting electromagnetics, which substantially reduce construction and siting costs. Thus, in many ways, EPRI is more flexible, less costly, and less complex than popular clinical modalities for molecular imaging, such as PET, or anatomical imaging, such as MRI.
Despite these advantages, EPRI has often been limited to small-animal imaging. The two primary reasons for this limitation against extending EPRI to clinical medicine are (1) the short signal lifetimes encountered in EPRI, which make image acquisition technologically challenging, and (2) the need to use higher RF/microwave frequencies to achieve the desired sensitivity, which can be challenging in terms of uniform magnetic field creation, tissue penetration for whole-body or large volume imaging, and power absorption within the tissue. While several solutions to image acquisition challenges relative to short signal lifetimes have been demonstrated, the remaining limitation of moving toward higher frequency operation for imaging is unmet, yet critical to making EPRI available for clinical, human applications.
Thus, a need persists to allow provide imaging systems and methods that can leverage the electron paramagnetic resonance phenomenon for imaging in clinical, human settings.